1. Field of the Invention
The present invention relates to a separation column which is used in high performance liquid chromatography or the like to separate components of samples and also to a liquid chromatography apparatus which uses it.
2. Description of the Related Art
In conventional high performance liquid chromatography or the like where a particulate-packed column is commonly used, increasing the amount of liquid delivered per unit time is needed to shorten the analysis time. However, to allow this while the same separation performance as before is provided, it is necessary to increase the surface area of the packed particulates by packing smaller particulates. Specifically, in the case of a conventional column which is a cylindrical container having an inside diameter of about 4 mm and filled with particulates of about 5 micrometers in diameter, it is possible to shorten the analysis time to a tenth if the particulates are made smaller to about 2 micrometers in diameter.
However, reducing the size of the particulates increases the flow resistance and therefore makes it necessary to enhance the whole analysis apparatus in pressure resistance since the liquid must be delivered at higher pressure.
As compared with the particulate-packed column, use of a monolith column, which is a skeleton like a three dimensional network having pores (channels, macropores and throughpores) integrated therein, provides a larger surface area. This column can have so large a porosity as not to increase the flow resistance. For example, such a column is a monolith type silica column formed by setting a porous block (monolith rod or monolithic silica rod) in a thin tube. Higher performance is aimed at by using this monolithic silica column.
However, since the porous block is difficult to form with precision in terms of outer diameter, bowing, etc., spaces are likely to occur between the thin tube and the porous block. Thus, as a first prior art technique, avoiding leakage of the mobile phase from the side surface of the column by coating the peripheral surface of the porous block with resin is disclosed in, for example, JP-A-1999-64314.
Also as a second prior art technique, it is known to heat a fiber-reinforced plastic tube in order to improve contact between the column frame and the monolithic absorbent after the monolithic molding is introduced into the tube.